content: /*
   * Copyright 2016 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package hu.akarnokd.agera;
  
  import android.support.annotation.NonNull;
  
  import com.google.android.agera.Condition;
  import com.google.android.agera.Observable;
  import com.google.android.agera.Updatable;
  
  import java.util.concurrent.atomic.AtomicBoolean;
  
  /**
   * Let's update() signals pass through while the condition returns true or removes itself
   * from the parent otherwise.
   */
  final class AgeraTakeWhile extends AgeraTracking<TakeWhileUpdatable> {
      final Observable source;
  
      final Condition condition;
  
      AgeraTakeWhile(Observable source, Condition condition) {
          this.source = source;
          this.condition = condition;
      }
  
      @NonNull
      @Override
      protected TakeWhileUpdatable createWrapper(@NonNull Updatable updatable) {
          return new TakeWhileUpdatable(updatable, condition, this);
      }
  
      @Override
      protected void onAdd(@NonNull Updatable updatable, @NonNull TakeWhileUpdatable wrapper) {
          source.addUpdatable(wrapper);
      }
  
      @Override
      protected void onRemove(@NonNull Updatable updatable, @NonNull TakeWhileUpdatable wrapper) {
          wrapper.remove();
      }
  }
  
  final class TakeWhileUpdatable
  extends AtomicBoolean implements Updatable {
  
      final Updatable actual;
  
      final Condition condition;
  
      final AgeraTakeWhile parent;
  
      TakeWhileUpdatable(Updatable actual, Condition condition, AgeraTakeWhile parent) {
          this.actual = actual;
          this.condition = condition;
          this.parent = parent;
      }
  
  
      @Override
      public void update() {
          if (condition.applies()) {
              actual.update();
          } else {
              remove();
          }
      }
  
      void remove() {
          if (!get() && compareAndSet(false, true)) {
              parent.removeUpdatable(actual);
          }
      }
  }
  